I have several parts and assemblies of an aircraft that were exported as pro-e parts from catia.

If they were all properly combined they would make up the entire aircraft, and that is what I am attempting to do. The problem is that they are not native SW parts and assy's. Each part is just an "imported" feature in the tree. Some of the assemblies are true assemblies which reference numerous external parts while some assemblies are just multibodied part files. The difficulty in combining these is that none of them have a common point of reference, the X,Y,Z planes are all kinda goofy in each part/assembly.

Now I know that with a single part file I can create my own coordinate system, then export the part out to IGES, STEP, etc. using that coordinate system, then re-import it and have a more sensible coordinate system in my new part. (though I cant really do that with individual parts becasue then it would totally screw up assemblies that reference them) I am wondering what is the best method of doing such a thing with an assembly though. Another thing that makes these assemblies difficult to work with is that as mentioned they consist of a bunch of "imported" parts with a fixed constraint, there's no real mates involved. Each assembly does contain one common part, a forward bulkhead. I would like this bulkhead (just an oval shaped piece of sheetmetal) to be coincident with the front plane and centered on the origin point. So my question is, how would I move all the parts in the assembly so they stay fixed relative to one another and re-orient them as I wish? I would also like to keep to a minimum importing/exporting as I worry it will affect the fidelity of my model. Hopefully I have explained this well enough to make sense.

thanks for any tips